Chlorinated dimethyl silicone polymers



Patented Jan. 27,1948 1 crrLoannrnn nmmrm smrcom: i POLYMERS, I Rob Roy McGregor. Verona, and Earl Leathen Warrick. Pittsburgh, Pa.,- asslgnors to Coming Glass Works, Corning, N. Y., a corporation of New York No Drawing. Application M4, 25, 1945,

. Serial No. 595.876

8 Claims. (01'. 260-607) This invention relates to new compositions of matter and methods of preparing them.

The present application is a continuation-inpart of our copendlng application Serial Number 432,530, filed February 26, 1942, now Patent No. 6 and the like. When the thread is coated with a 2,384,384, issued September 4, 1945, and assigned chlorinated dimethyl silicone and baked to a to the assisnee of the present invention. tack-free state, not only is the fuzzing problem The primary object of the present invention completely solved, but also the tensile strength is to prepare chlorinated dimethyl silicone polyof the thread is considerably increased. The mers. Other objects and advantages will be 10 products of the present invention are also useful apparent from the following description and as additives to lubricants such as petroleum oils claims. to improve their resistance to extreme pressure.

In accordance with our invention, we have'dis-= For a better understanding of our invention covered that polymeric dimethyl silicone may be reference should be had to the following examples chlorinated to yield products which are useful which are given by way of illustration and not either as intermediates in the preparation of limitation. other materials or which are useful in their own Example 1 right as coating compositions (as Wm be later The cyclic pentamer of dimethyl silicone was described). The chlorination of the dimethyl chlorinated by passing chlorine gas through it Silicone polymers is preferably carried out by at room temperature in the sunlight until analysis passing chlorine through the polymers m liquid showed that it contained about 1 chlorine atom state at a temperature within the range of about per carbon atom or one chlorine atom per cyclic 3 and preferably the presence unit. When the chlorinated product was dissunlight As a result such treatment the tilled only about 20% of it boiled in the neighborviscosity of the silicone increases and if continued hood of the boning point of the pentamen The for a suflicient time a waxy solid is produced. remaining 80% was not only higher boning but As high as 65% by weight of chlorine can be was also much more viscous. Continued heating introduced into the silicone in this manner. of the latter portion resulted in gelaflon If the chlorination is stopped at some intermediate point, a viscous liquid is obtained which, Ewllmllle upon being heated,increases rapidly in viscosity The cyclic pentamer of (methyl silicone was u t t t y a g s Produced rather than chlorinated by passing chlorine gas through it at waxy Sond- The melting point of the waxy nd room temperature and in the sunlight until anaproduced by extended chlorination depends upon lysis showed that it contained about 1.09 chlorine the amount of chlorine introduced, the larger the atoms per carbon atom or about 10 chlorine atoms amount the higher the melting point. To obtain per cyclic unit The product was a clear waxy the highly chlorinated products, it is advisable sand w a melting point of about when to employ an inert solvent S as carbon tetra heated in an open beaker without a catalyst for chloride- We have found that i is immaterial about 15 hours at about 125 C. HCl was evolved whether the starting silicone is a cyclic polymer' and the material lost its waxy characteristics and such as the tetramer or pentamer, or whether it became a resinous 501m when treated with is a chain polymer Whose terminal groups are aluminum chloride and heated at 175 C. it bey chlorine' or trimethyl silicon units or came a tacky resinous solid in four hours. The combinations thereof 5 effect of chlorine content on melting point was The chlorinated products of our invention demonstrated in the following manner. When whether in a low or high degree of chlorination 0 8 atom per carbon atom was imroduced into are useful as intermediates in the preparation h cyclic pe'ntamer the product had a melting of other compositions. For example, the chloripoint of C when the chlorine content was ted cyclics having from one to two chlorine 1.04 chlorines per carbon atom, the melting point atoms per cyclic unit are useful in the prepara- 50 was C and hen it was 1 20 the melting tion of thermally stable liquids of low pour points mm s 5 C w as will be described in the examples. However, p Exam le 3 we have found the products to be particularly useful in their own right as coating materials for As in Example 2, the cyclic tetramer of dimethyl glass threads. The latter are composed of a 55 silicone was chlorinated at room temperature large number of fine attenuated glass fibers, some or which break during sewing operations causing fuzzing of the thread and seriously hindering the rapid and effective fabrication of textile fabrics until analysis showed it to contain about .37 chlorine atom per carbon atom or about 3 chlorine atoms per cyclic unit. When the chlorinated material was heated to 250 C., it formed a semi-solid mass. From this product an oily liquid was extracted with benzene which, on heating overnight at 230 C. became solid.

Example 4 34% by weight of slightly chlorinated cyclic tetrameric dimethyl silicone (about .l2 chlorine atom per carbon atom or about 1 chlorine atom per cyclic unit) was added to a mixture of chain polymers of dimethyl silicone having a viscosity of 112 centistokes. These chain polymers, as well as those employed in the following examples, contained terminal hydroxyl groups and were prepared as described in our copending application Serial Number 432,530, mentioned above. The resulting mixture was heated for two hours at 220 C. The viscosity increased to only 140 centistokes but the pour point was about 10 degrees lower than that of the original mixture of chain polymers despite the fact that the pour point of the cyclic tetramer per se is above that of the chain polymers.

Example 5 Example 6 73.3% by volume of chain polymers of dimethyl silicone obtained by distilling off the cyclic polymers and having an average molecular weight of about 2000, a viscosity of about 490 centistokes and a pour point of --60 C. was mixed with 26.7% by volume 01 the cyclic tetramer of dimethyl silicone which had been chlorinated until it contained .25 chlorine atom per carbon atom. The mixture was refluxed for 6 hours at 175 C. and then for 6 hours at 200 C. The product had a viscosity of 803 centistokes and a pour point of 70 C.

Example 7 The cyclic pentamer of dimethyl silicone was chlorinated by passing chlorine gas through it at room temperature until analysis showed that it contained about 2.5 chlorine atoms per carbon atom. When a mixture of the chain polymers of dimethyl silicone and of the chlorinated pentamer was heated at 140 C. the initial viscosity of 333 centistokes increased from two hours heating to 1180 centistokes: after six hours heating to 2190 centistokes; and after nine hours heating the material had become a rubbery resin. The process was repeated using 2% of the chlorinated pentamer and again the polymeric dimethyl silicone was converted to a rubbery resin on heating at 140 C. When only 0.2% of the chlorinated pentamer was used, the viscosity of the polymeric dimethyl silicone rose from 113 to 130 centistokes after 22 hours heating at 150 C.

Example 8 A mixture of chain polymers of dimethyl silicone and 10% of chlorinated cyclic pentameric dimethyl silicone (about 2.5-3.0 chlorine atoms per carbon atom) on being heated for nine hours at C. resulted in a stringy rubbery resin which was about 50% soluble in benzene. The benzene solution was used to impregnate a glass tape which was then cured to a tack-free condition by being heated for 24 hours at 230 C. and was not further changed by 48 hours additional heating. The impregnated tape after curing felt rubbery and snapped back into position when sharply bent. It also showed remarkable elasticity and ability to completely recover when stretched in a direction diagonal to the weave, the stretch with and across the weave being restricted by the lass fibers themselves.

Example 9 A mixture of chain polymers of dimethyl silicone was chlorinated until its chlorine content was about 6% by weight and its viscosity about 75,000 centistokes. The product was heated at 230 C. with 3.7% by weight of boric oxide until a rubbery solid was obtained. The latter possessed considerable elasticity without the property 01' "cold flow" which is common to most dimethyl silicone polymers treated in like manner with boric oxide.

Example 10 Liquid dimethyl silicone prepared by the hydrolysis of dimethyldiethoxy silane in the presence of sulfuric acid and having a viscosity of 500 centistokes was chlorinated by passing chlorine gas through it at room temperature in sunlight until analysis showed it to have 5.7% by weight of chlorine. The chlorinated product was heated at C. Its viscosity slowly increased until finally it became a homogeneous el which was soluble in benzene. Glass fiber tapes were impregnated with the benzene solution of the gel and the solvent volatilized. The impregnated tape was then heated at 250 C. until the coating became tack-free and hard. Further heating at the same temperature for many hours left the tape essentially unchanged.

Example 11 Liquid dimethyl silicone having a viscosity of 500 centistokes was chlorinated in the manner of Example 10 to 9.4% chlorine content. The product was dissolved in CC]; to make a 5% solution. Glass thread was dipped into the solution and then baked to dryness. It was found that the strength of the thread had increased; its grist and stillness had changed only slightly. On being subjected to sewing operations there were no breaks or fuzzing whereas the untreated thread when subjected to the same test broke twice and was very fuzzy through the entire operation.

We claim:

1. The method which comprises passing chlorine through a cyclic dimethyl silicone polymer until it is slightly chlorinated. mixing the resulting product with chain polymers of dimethyl silicone having terminal hydroxyl groups and heating the mixture to cause a reaction.

2. The methodwhich comprises chlorinating a cyclic dimethyl silicone polymer until it contains from approximately 1 to approximately 2 chlorine atoms per cyclic unit, mixing the resulting product with chain polymers of dimethyl silicone having terminal hydroxyl groups, and heating the mixture to cause a reaction.

3. The method which comprises chlorinating cyclic tetrameric dimethyl silicone polymer until it contains from approximately 1 to approximately 2 chlorine atoms per cyclic unit. mixing the resulting product with chain polymers oi. dimethylsilicone having terminal hydroxyl groups, and heating the mixture to cause a reaction.

4. The method which comprises reacting a chlorinated cyclic dimethyl silicone polymer with chain polymers of dimethyl silicone having terminal hydroxyl groups.

5. The method which comprises reacting chlorinated tetrameric cyclic dimethyl silicone polymer with chain polymers of dimethyl silicone having terminal hydroxyl groups.

6. The method which comprises reacting chlorinated pentameric cyclic dimethyl silicone polymer with chain polymers of dimethyl silicone having terminal hydroxyl groups.

ROB ROY McGREGOR. EARL LEA'I'HEN WARRICK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,258,218 Rochow Oct. 7, 1941 2,258,219 Rochow Oct. 7, 1941 2,258,222 Rochow Oct. 7, 1941 2,298,295 Hyatt Oct. 13, 1942 2,347,733 Christensen May 2, 1944 2,371,050 Hyde Mar. 6, 1945 2,384,384 McGregor Sept. 4, 1945 OTHER REFERENCES Taylor, Journal American Chemical Society," vol. 66,pages 842-843 (1944).

Ushakov, "Chemical Abstracts, vol. 32, page vol. IV, pages 625 and 629.

Beilstein, Handbuch der Org. Chem, 4th ed., 

